Gasification of carbonaceous solids

ABSTRACT

BONS, CONTAINING FROM 1 TO 7 CARBON ATOMS, ETHYLENE COMPRISING AT LEAST 20% BY VOLUME OF SAID GASEOUSS HYDROCARBONS; C. REMOVING THE PRODUCT STREAM FROM THE PYROLYSIS ZONE; D. RECOVERING THE GASEOUS HYDROCARBON PRODUCTS.   1. A PROCESS FOR PRODUCING GASEOUS HYDROCARBONS HAVING FROM 1 TO 7 CARBON ATOMS FROM SOLID CARBONACEOUS MATERIAL COMPRISING: A. FORMING A TURBULENT GASEOUS STREAM COMPOSED OF CARRIER GAS, WATER, CHAR, AND PARTICULATE CARBONACEOUS SOLIDS, SAID SOLIDS HAVING AN INDIVIDUAL MAXIMUM PARTICLE DIMENSION OF LESS THAN 1.0 INCH, SUCH THAT THE SOLIDS AND WATER ARE INTIMATELY ADMIXED AND ENTRAINED WITHIN THE GASEOUS PORTION OF THE STREAM SAID WATER BEING PRESENT IN SAID STREAM IN AN AMOUNT WHICH IS AT LEAST 2.0 WEIGHT PERCENT BASED UPON THE AMOUNT OF CARBONACEOUS SOLIDS IN SAID STREAM; SAID CARRIER GAS CONTAINING LESS THAN 1% BY VOLUME OF OXYGEN; B. HEATING THE COMPONENTS OF SAID STREAM TO A TEMPERATURE RANGING FROM BETWEEN ABOUT 1200* F. AND ABOUT 2500* F. IN A PYROLYSIS ZONE FOR A PREDETERMINED RESIDENCE TIME SO THAT AT LEAST A PORTION OF SAID CARBONACEOUS SOLIDS ARE CONVERTED TO GASEOUS HYDROCAR

NOV. 5, 1914 G, M, MALLAN ETAL GASIFIGATION 0F CARBNACEOUS SOLID FiledOct. 19, 1972 l 555k vu xwmxswww wwm f %h\\ m ww m@ United States PatentO U.S. Cl. 48-209 16 Claims ABSTRACT OF THE DISCLOSURE A continuousprocess for converting particulate carbonaceous solids to gaseoushydrocarbons (from 1 to 7 carbon atoms per molecule of gas) by the rapidpyrolysis and in situ conversion of a portion of the pyrolysis productcomprising heating a turbulent high velocity gaseous stream composed ofcarrier gas, Carbonaceous solids and at least 2.0 weight percent waterbased upon the Weight of Carbonaceous solids and heating said stream ina pyrolysis zone at a temperature ranging from between about 1200 F. toabout 2400 F. until at least a portion of said solids are converted tothe desired gaseous hydrocarbons.

BACKGROUND OF THE INVENTION This is a continuation-in-part of ourpending application Ser. No. 153,358, filed June 15, 1971 onGasification of Carbonaceous Solids now abandoned.

The art has long sought a continuous process for the conversion ofCarbonaceous materials such as coal and solid wastes containing organicmaterial to gaseous hydrocarbons and/or petrochemical feed such asethylene. The effort stems in part from increased interest in the use ofsuch gas as a raw material for the synthesis of chemicals and liquidfuels, and in part from the need to develop methods for gasifying coaland solid wastes containing organic matter to ensure a long range supplyof energy and chemicals in the form of gas. Gasification of suchmaterials yields a product that can be handled with maximum convenienceand minimum cost, and in addition greatly extends the uses to which suchsolid fuel sources may be put. Where solid wastes containing organicmatter are gasied, there are the added ecological advantages of disposalof the wastes; by recycling them for use in the energy cycle thus addingto the total resources available.

In conventional processes for the conversion of carbonaceous materialsto pipeline gas, a single reactor vessel is employed for the requiredconversion with the carbonaceous solids being pyrolyzed at hightemperatures to cause it to release its volatilized hydrocarbons as avapor within the vessel and these vapors are contacted with hydrogenwhile maintaining the reactants under high pressure and high temperaturewithin the pyrolysis `vessel to convert the volatilized hydrocarbonscontained therein to pipeline gas. This system requires the use ofpressure lock hoppers to feed Carbonaceous solids into the reactorvessel and to remove solids from the vessel. The use of such hoppersgreatly increases the cost of such systems. Further, carbonaceousmaterial which has agglomerative tendencies must be pretreated prior tobeing hydrogasied in order to prevent coking during the hydrogasicationstep.

The art has long sought a continuous ow process for the conversion ofsolid carbonaceous materials to gaseous hydrocarbon without thenecessity of passing solid materials through pressure differentials.

Another problem facing us is the disposal of both industrial anddomestic solids such as trash, rubbish, garbage, etc. is becoming animmense national problem. The

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cost of this service presently ranks third behind public schooling andhighways as a municipal expense in the United States. The cost per unitof trash disposal and the number of units of trash per person is risingannually. It is estimated that each individual in the country gencratesbetween 4-6 pounds per day of solid waste, and that the industrialoutput is equivalent to approximately ive pounds of solid waste perperson per day. The cost of disposal varies from 5 to 30 dollars per tonof trash. Previous methods of trash disposal, such as land iill arebecoming impossible while others such as incineration are costly andresult in air pollution problems. Less costly and more eiiicientdisposal means for solid waste appear mandatory.

A second aspect of this problem is that the United States is consumingits natural resources especially natural gas at an ever increasing rate.In the normal materials utilization cycle, raw materials are collected,processed into useful products, utilized by consumers for varying spansof time, and then consigned to a presumably uncoverable wasteland, thecity dump.

Because of these problems, many proposals have been put forth to utilizeand recover values from solid wastes. Aluminum companies and glasscompanies will purchase used cans and bottles for reprocessing.Engineering studies and plant designs have been prepared to advance theconcept of utilizing the heat produced by garbage incineration tooperate electrical and desalination plants.

The idea of recovering metal values from -waste solids is old in the artand is an integral part of the steel making industry.

However, the art must now develop processes to utilize both the metallicand non-metallic portion of waste solids as a raw material since theserepresent a large portion of the waste solids. Simple incineration ofthe organic portion of waste solids to produce utilizable heat is notthe solution for several reasons. The off gases produced duringincineration contain air pollutants, such as SO2. NOX, CO and ash. Thesepollutants must be trapped or diminished which requires costly devicessuch as electrostatic precipitators, scrubbers, etc. to avoid airpollution. In addition, organic waste solids are a poor fuel, andrequire very high combustion temperatures. What is needed is anefficient, economical method for handling the conventional waste solidsproduced by society which will recover chemical and fuel values fromboth the inorganic and organic portions of waste solids whilesubstantially reducing the volume of gaseous efliuent which must betreated to eliminate air pollution during processing.

The goal of totally recycling the raw materials contained in municipalsoid wastes has become almost a holy grail to many members of ourchanging society. Although the idea is old, it was they who dramatizedthe quest, and when Congress passed the Solid Waste Disposal Act of1965, the American people set their sights on the same goal. Morerecently, when Congress passed the Resource Recovery Act of 1970, thegoal was more clearly deiined and the quest may now receive signicanttaxpayer support. The end result should not only be a beautification ofthe American scene, but also a reduction in the financial drain on thetaxpayer who is now asked to contribute toward the achievement of thisgoal. The present iinancial drain is truly staggering. In 1968, about$4.5 billion was spent by municipalities to collect, and either bury orburn our solid wastes. If something is not done to change wasteelimination procedures, the cost estimates for 1980 range from $12.5 to$16.5 billion. Although about three quarters of these costs go forantiquated and d flicult to change collection procedures, there is hopeto significantly reduce, or even eliminate, the current disposal coststo the urban community.

At the present time, a significant amount of discarded raw materials isbeing recycled to the economy by many companies engaged in Americassecondary materials industry. Large quantities of metals, an appreciableamount of paper, and some glass is being collected, upgraded and reused.However, except for tin and aluminum cans in some scattered areas of thenation, only a small fraction of our reusable resources are beingrecovered once they enter the municipal collection stream. A typicalbreakdown of municipal refuse is shown in the following Table 1, andupto now the difiicult problem has been how to separate the vast amount ofcontaminated materials from the heterogeneous mass, and recover thepotential values shown in this Table. In the past few years, Americanindustry has tackled this problem, and answers are indeed beginning tocome forth.

We have invented a process which overcomes the above problems. The keyto our process lies in converting the unuseable organic portion of solidcarbonaceous wastes to gaseous chemical and fuel values using anefficient, lw-cost, high capacity pyrolysis operation. Over one millioncubic feet of gas can be obtained per ton of wet as-received municipalrefuse. This process has been researched on a small continuous benchscale unit and in a pilot plant.

Our novel pyrolysis process is based upon the heating of shreddedorganic waste materials in the absence of air using a novelheat-exchange system. This method was developed to maximize gas yieldsand thus generate the maximum gas chemical and fuel value per ton ofwastes. At the present time, organic chemical and fuel gas yields ofgreater than 40 weight percent are being obtained from oven-dried,inorganic-free feed material. This gas has an average heating value offrom 900 to about 1100 B.t.u. standard cubic foot (scf.) and can be usedas a replacement for pipeline gas. Pyrolysis of organic waste materialsalso produce char, condensable gases and a water fraction. Thedistribution of these products is the most important economic factorinvolved in commercial pyrolysis equipment. Most other prior art unitsproduce relatively little organic gases unless high pressurehydrogenation is employed. Aside from the organic liquid, or oil yieldsof 40 wt. percent obtained in a typical run, about 35% char, 10% gasesand 15% water are also obtained. The gases and some of the char are usedfor a heat source in carrying out the process, and the oil and remainingchar can be sold as a fuel or raw chemical.

The pyrolysis process is flexible with regard to feed materials. So far,the following waste products have been converted to useful chemical andfuel values: municipal solid wastes, tree bark, rice hulls, animal feedlot wastes, and shredded automobile tires. In the case of tires, a charis produced which is recyclable into new tire manuacturing as carbonblack. Tests conduced on this product shows that moduls of elasticityand tensile strength of the compounded rubber approach to within 75 to85% of the properties obtained when general purpose carbon black isused.

4 SUMMARY `OF THE INVENTION It is the purpose of this invention toprovide an efiicient economical method of recovering gaseous chemicalvalues from solid wastes, thereby not only eliminating or greatlyreducing the volume of the waste solids, but also having the addedeconomic advantage of recovering chemical and fuel values from solidwastes for recycling into the economy as raw materials and which alsowill facilitate the segregation and recovery of metallic values from theinorganic portion of conventional solid wastes.

This invention is directed to an efficient economical process forproducing gaseous hydrocarbons containing from 1 to 7 carbon atoms permolecule of gas, which gaseous hydrocarbons are useful as heating fuelsor petrochemical feedstocks i.e., ethylene. This invention is directedto a process for recovering chemical and fuel values from conventionalwaste materials. The waste materials being composed of both organic andinorganic solids which solids are capable of being divided into discreetparticles by comminuting the waste material solids until the particlesize of said waste material has a maximum particulate dimension of lessthan 1.0 inch. The process comprises forming a high velocity turbulentgaseous stream composed of a pyrolysis carrier gas, particulated wastesolids, water and hot particulate char in a pyrolysis zone, such thatthe particles of waste solids, char particles and water are intimatelyad-miXed and entrained within the gaseous portion of the stream; heatingthe waste material in said stream to a temperature of from between about1200 and about 2200 F. in the pyrolysis zone, the residence time of saidwaste solids in said zone being less than 10 seconds; removing theproduct stream from the pyrolysis zone; and separating and independentlyrecovering volatilized products and solids from said product stream. Inour novel process, organic chemical values in the waste solids arevolatilized and pyrolyzed by heat to organic chemical and fuel valueswhich are eluted from the organic solids by vaporization and rapidlyremoved therefrom to minimize thermal decomposition of these values. Theorganic chemical and fuel values emerging from the pyrolysis zone of ourprocess can be readily separated from the inorganic portion of thepyrolyzed waste solids by conventional classification systems. Our novelprocess can be beneficially utilized to recover chemical values fromwaste solids which are essentially organic in nature. The organicchemical efliuent from the pyrolysis zone contains a raw material forfurther processing in accordance with the teachings of this invention.The volatile organic values, which are a valuable raw material, can beseparated from the product and carrier gas and further treated toproduce useful products. The metallic values in the segregated inorganicsolids can be recovered therefrom by conventional processing.

In a preferred embodiment of our invention the gaseous stream containsfrom about 7.0 to about 18.0 weight percent water and is heated until asubstantial portion of the carbonaceous solids contained therein isconverted to ethylene (greater than 20 weight percent) with theremainder of the gaseous hydrocarbons being utilized to process heat forthe pyrolysis zone. Thus, there is provided an efiicient economicalmethod of recycling solid carbonaceous material i.e., municipal trash,industrial and agricultural Waste products, etc. as valuable rawmaterials.

BRIEF DESCRIPTION OF THE DRAWING The drawing shows in schematic outlinean arrangement of equipment for carrying out the novel processes of thisinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS This invention isconcerned with the production of gaseous hydrocarbons for use as asource of fuel and/or as a raw material in chemical processing. Such gasis composed preferentially of ethylene, methane, and hydrogen and cancontain other gaseous hydrocarbons having from 1 to 7 carbon atoms;i.e., methane, ethane, propane, butane, etc. which do not interfere withits intended use. The gas produced by our novel process can be treatedby conventional processes to remove any impurities which are deemedundesirable, i.e., sulfur compounds, carbon dioxide, carbon monoxide,etc.

In effect our process is a one stage process having several chemicalprocesses effected sequentially in the single stage, namelydevolatization of the carbonaceous solids, cracking of the volatiles,water-gas-shaft reactions on the residual carbonaceous solids andhydrogenation of the cracked volatiles.

In this invention we are dealing with the carbonaceous materials ofconventional solid wastes containing organic matter produced in oursociety. Municipal solid wastes can contain the widest variety ofingredients, e.g., glass, metal, water, organic products such as paper,automobile tires, plastics, vegetable and animal material, etc.Industrial wastes include rubber, plastics, agricultural wastes manure,waste wood products, cannery wastes, etc. While our process can handleconventional waste solids without prior segregation of the inorganicmatter therefrom; preferably the inorganic materials are segregatedfro-m the waste solids and only that portion of the waste solids whichis composed substantially or organic (carbonaceous) materials or matteris treated by the present process. The degree of segregation of organicmatter from the original waste solids is variable, since totalsegregation may impose uneconomical cost factors on the overall process.Waste solids can be segregated by using conventional separationequipment and processes.

The waste solids segregated or unsegregated, are comminuted to aparticulate found useable in our invention wherein the maximum dimensionof the particles is no greater than one inch, and in the preferredembodiment of our invention the particles of the comminuted Waste solidshave a maximum dimension of 0.25 inch or less. By the term maximumdimension is meant the largest dimension, e.g. either length or width orthickness, of the individual which should exceed this upper limit mayhave smaller dimensions and can consist of chunks having essentiallythree dimensions, pieces of paper, plastic iilm, plant leaves havingessentially two dimensions and/or strips of material which areessentially one dimension e.g., organic filaments. The size and shape ofthe particles as well as the density will affect the pressure dropwithin the system and the heat transfer into the particles which willnecessitate adjustments of residence times within the pyrolysis zone toinsure that the particles of organic matter are heated to the desiredreaction temperature in the zone. For this reason we deem it preferablethat the waste solids be comminuted and intermixed to produce asubstantially uniform mixture.

The amount of water to be added in our process is of course dependent onthe nature of the carbonaceous materials processed, but at least 2weight percent of water based on the weight of carbonaceous solids ispresent. In general we have found that from about 7.0 to about 18.0weight percent water based upon the Weight of carbonaceous solids beingtreated gives beneficial results. The required water can be separatelyinjected into the stream as it is formed or it can be added to particlesprior to formation of the stream.

An essential feature of this invention is the heating of the organicwaste solids to a temperature of from about 1200 to about 2500 F.preferably from about 1400 to about 1600 F. while the waste solids areentrained in a turbulent gaseous stream composed of carrier gas, wastesolids, water and hot particulate char. The stream is contained within apyrolysis zone for a period of less than seconds preferably from about0.1 to about 0.6 seconds. In general we have found that organic wastesolids from municipal sources can be advantageously treated by theprocess of our invention by heating the organic waste solids to atemperature of from between about 1400 to about 1600 F. in the pyrolysiszone with a residence time ranging between 0.1 to 2 seconds. Therelationship between temperature and residence time can be varied tooptimize yields of the gaseous organic chemical and fuel values. If thetemperature and/ or residence times are too low, the Vaporization andpyrolysis of the solid waste is incomplete. When the temperature and/ orresidence time is too high, the pyrolysis products are degraded givinghigh yields of carbon monoxide, hydrogen and carbon dioxide and lowyields of the desired gaseous chemical and fuel values.

By the term turbulent stream is meant a stream of gas flowing through apyrolysis zone, e.g., -a pipe shaped reactor vessel, wherein the ow isturbulent in nature, e.g., having a Reynolds ow index number greaterthan 2000 preferably about 2500.

In operation, a low ratio of about 0.2 to about 2.0 pounds of mixedgases to each pound of waste solids is all that is required to obtain aReynolds flow index number of 2000 or greater when the pyrolysis chamberhas a diameter of 3 inches or greater. For example, with a 10 inchdiameter chamber, about 0.7 pounds of gas for each pound of solids isall that is required to maintain a turbulent iow in the chamber. Laminarflow in the pyrolysis zone must be avoided because a flow system wouldtend to severely limit the contact between the char, water andcarbonaceous material and rate of heat transfer within the pyrolysiszone. In the normal practice of this invention the carrier gas, water,hot char and waste solids are introduced into one end of the pyrolysisvessel and rapidly intermixed and dynamically contacted with each otherand lblown through the vessel to permit the requisite heat transfer totake place. The heat required to pyrolyze the organic matter and removethe volatile organic chemical values can be provided all or in part fromthe sensible heat in the char particles, preferably all the heat issupplied by hot char. From about 2 pounds to about 10 pounds of hot charis used for each pound of solid waste. The use of hot char as the heatsource in the pyrolytic zone has many advantages. Because of its heatcapacity and density, a much lower volume of char is needed to heat thesolid waste than would be the case if hot carrier gas alone was used.The hot char comes in intimate contact with the solid waste in theturbulent gaseous stream for eflicient heat transfer. The water, in theform of steam can also furnish some of the reaction heat.

The carrier gases found useable in this invention to effectuate thethermal elution of the waste solids particles should not oxidize thechar, organic matter and organic chemical values formed duringpyrolysis. Thus the gas stream should be substantially free of air,oxygen, and the like, that is the stream should contain less than 4% byvolume oxygen, preferably less than 1% by volume oxygen. The amount ofoxygen is minimized to minimize oxidation of organic values includingthe liquid chemical and fuel values. Exemplary of gases suitable for useas carrier gases in our invention are, nitrogen, argon, CH4, H2, carbonmonoxide, Hue gases, carbon dioxide steam and any other gas which willnot deleteriously react with or oxidize the organic portion of thematter within the system. In a preferred embodiment of our invention werecycle the carrier gas back to the pyrolysis zone after the organicchemical values are removed therefrom.

The particulate char is added to the waste solids in the preferredoper-ation of our invention to provide all or a portion of the heatrequired for thermal elution. The selection of an optimum char-to-wastesolids weight ratio will of course be dependent upon the heat transferrequisites of the system. Since part of the heat of pyrolysis can besupplied by the carrier gas and steam, the temperature, flow rate andresidence time in the reactor can be calculated by well known methodsfor a particular system. In general, for economys sake we prefer toutilize the char particles for the main source of heat for the pyrolysisdue to their density and the beneficial heat transfer coefficients builtinto the system. Heat energy can also be furnished to the pyrolysis zoneby indirect means such as electrical heating through the zone wall.

The pyrolysis portion of the system is designed to rapidly heat thecarbonaceous particles to a temperature ranging from 1200 to 2500 F. torecover the maximum amount of volatiles therefrom, preferably between atemperfature of from about 1400 F. to about 2200o 'F. The selection of aparticular temperature in this range will of course be dependent uponthe particular organic waste solids employed and the residence time ofthe waste solids in the pyrolysis zone.

The ef'liuent from the pyrolysis zone is composed of char, volatilizedorganic fuel and chemical values, product gas, and carrier gas. Thevolatilized organic fuel and chemical values are cooled to a temperaturebelow the temperature of pyrolysis to minimize degradation of theorganic chemical values. The char solids can be readily separatedtherefrom by any conventional solids/gas separator such as a cyclone andthe like. The volatilized organic chemical values and carrier gas can beseparated vand recovered by conventional separation and recovery means.When the waste solids passed through the pyrolysis zone containinorganic matter such as metal and glass particles intermixed with thechar produced by the organic portion of the waste solids, the organicand inorganic solids can be readily separated by conventional airclassification systems. In fact the pyrolysis of the organic solidsincreases the density differential between such solids and actuallyfacilitates the separation. However, the solids containing bothinorganic and organic solids can be recycled through the pyrolysis zoneto provide the necessary heat without prior separation. When thepyrolyzed solids are separated, the latent heat found in the inorganicsolids is utilized to provide heat for the pyrolysis zone in order toincrease the elhciency and economics of the system e.g the heat of theinorganic solids can be used to heat the recycle gases. Alternately, theinorganic solids can be separated from the char by conventional means ifdesired. Of course it will be obvious to those skilled in the art thatthe hot inorganic solids recovered from our invention are in anexcellent form and condition for further processing by conventionalprocesses to recover metallic or inorganic chemical values therefrom andthat this factor adds further attractive economics to our novel process.

By the term Volatilized hydrocarbons as used in this application ismeant the product gases produced by pyrolysis of the Waste solids and ingeneral these consist of saturated and unsaturated hydrocarbons havingfrom 1 to 7 carbon vatoms and lesser amounts of carbon dioxide, carbonmonoxide and hydrogen. The product gas stream also contains undesirablegaseous products such as NH3, HCl, H and water which should be removedfrom the product gas stream by conventional means such as cooling andchemical scrubbing, etc.

Initially the system is started up by using hot char from other sources,but after waste solids have been pyrolyzed as described herein,sufficient hot char is produced as required by the system, and in factis produced in excess. The excess char can be readily utilizable infurther processing to provide new materials, which enhances the totaleconomics of our process, such as fuel for use in a power plant or a rawmaterial source for the chemical industry. These excess char can bebriquetted by conventional means and utilized as a source of fuel orcoke.

The excess :char particles produced by our novel process can 4also bedegasitied, if desired, by heating Vto temperatures ranging from about1200 F. to 1800a F. or higher to yield a hydrogenrich gas which issaleable as premium fuel. The gas can be upgraded into pure hydrogen, orused for hydrotreating the heavier volatilized chemical values producedduring the present process.

`Char degasiiication can be carried out in lseveral ways which, insubstance, amounts to director indirect heating. In direct heating, thechar is contacted with sutiic-ient oxygen from a suitable source, suchas air, to bring the stream by lcontrolled combustion up to the desireddegasiiication temperature. This can be accomplished in -a transportreactor similar to the pyrolysis reactor or in a uidized bed reactor.

Preferably, the char is degasified by indirect heating which yields agas stream containing 70 or more percent by volume hydrogen. This may'be 'accomplished in a reactor simil'ar to a tubular heat exchanger inwhich the char is blown through the tubes in a dense -or dilute phaseand fuel is burned with air or another suitable source of oxygen inladjacent tubes to supply the heat required for degasi'lication.

Alternatively, the `same result can be accomplished by the combustion ofthe fuel in tubes located in a tlu'idized bed of the char. Afterseparating the char from the evolved gases, the char is cooled forultimate use as `a high grade fuel.

Where it is desired to produce a low sulfur char, from waste solidscontaining large amounts of sulfur, sulfur reduction can be accomplishedduring pyrolysis, superheating and/ or degasication vof the resultantchar.

Desulfurization during pyrolysis can also be achieved by having a solidsulfur acceptor, such as lime or iron oxide, present in the zone duringpyrolysis. The sulfur combines with `iron oxide to form pyrrhotite. Bothare iron oxides, `and pyrrhotite is magnet-ic and can be removed, inaddition to -any iron pyrite naturally present, from the product char bymagnetic separation. This can conveniently be iaccomplished with aminimum cooling of the char to conserve the heat requirements forprocessing.

Desulfurization may also be achieved during pyrolysis by enriching thegas stream with hydrogen, preferably part of the hydrogen releasedduring degasication. The hydrogen fed to pyrolysis zone reacts withsulfur to form hydrogen sulfide which lis later removed by conventionalmeans such as scrubbing; hydrogen also enriches the volatilizedhydrocarbons. In the preferred embodiment of our invention we use acarrier gas containing at least 2() parts by volume hydrogen based uponthe 'total volume of carrier gas used.

Desulfurization may also be achieved by superheating the char byemploying as the transport gas, a gas enriched with hydrogen. This gasreacts with the `sulfur in the char to achieve additional sulfurreduction of the product char. As with desulfurization during pyrolysis,the hydrogen employed obtained by the recycle of off gases from chardegasi-ficati-on before or after purification.

Where it is desired to recover the 'sulfur from the p-roduct char, thechar which `is already at `an elevated temperature is merely heated toabout 2300" to 2800 F. at `ambient pressures in the non-oxidizingenvironment for periods up to about 20 minutes. This results insubst-antial sulfur reductions from the char.

When the char is degasiiied by indirect heating, maintaining pressure atfrom about 15 to about 100 p.s.i.a. and using a hydrogen-rich transportgas enhances additional sulfur removal during degasification. Underthese conditi-ons char can be desulfurized as well as degassed withinreactor times of about ten minutes. This desulfurization can be`achieved since the inorganic sulfur has been essentially removed by thesulfur acceptor in previous treatment.

The following description of the drawing teaches a typical example ofthe present process and is not intended to be a limitation thereof.

As shown in the Figure, the particulate carbonaceous solids enter theboundary of the unit through line 2, and

pass into feed bin 4 for surge storage. Therein the feed is purged of-oxygen by vacuum or an oxygen lfree gas streams purge, such as anitrogen, carbon dioxide or carrier gas stre-am. The feed is thenmetered into the system through a gas tight Valve 6 into line 8, throughwhich passes sufficient recycle gas to transport the particulate solidsthrough the rest of the :pyrolysis .system at the proper operatingvelocity. The recycle gas and particulate carbonaceous solids then picksup sufficient water from line 10 to complete the requiredwater-gas-shift reaction. Optionally water as steam can be passeddirectly into pyrolysis reactor 12, preferably heated to a temperature-near the desired pyrolysis temperature. Sufficient 4hot char to providethe heat to carry out the pyrolysis reaction is added through line 42.The reaction takes place in reactor 12 where the temperature is raisedto between 1,200 and 2,400o F. The residual char and hot gases from thereactor are removed through line 14, and the Isolid-s are separated fromthe hot gases in cyclone 16. The new char produced in reactor 12 is of asize large enough to be removed in cyclone 16. The original hot char isreduced t-o an -ash of a smaller -size which can be classified andseparated when passed into cyclone 44. The new char is passed ou't ofcyclone 16 through line 18 where it joins line 20 carrying air andrecycle gas into char heater 26. After the new char is burned to asufficiently high temperature in char heater 26, it is passed out'through line 28 where the hot char i-s removed from the combustiongases in cyclone 30. Less than a stoichiometric amount of oxygen is usedto provide that the heated char gas stream contains substantially nooxygen after combustion in heater 26. These gases leave 'through line 32and pass into a waste heat recovery system 34. The hot char passesthrough line 36 into a surge bin 38 where it is temporarily stored andfed into the lpyrolysis system through metering valve 40 and line 42 tojoin line 8 containing the pyrolysis feed materials. This waste ashproduct from cyclone y44 leaves through line 46, is cooled in -ashcooling unit 48 4and removed lfrom the system through line 50. Theproduct gases of the pyrolysis reaction leave cyclone 414 through line52 and are quenched in quenching tower 54 with water inert solventand/or inert gas. The condensables are mostly water land a small amountof organic liquids which leaves the quench system through line 56 and ispumped through pump 58 into line 60 for disposal and/or recovery viaconventional facilities (not shown). The cooled product gases leave thequench tower 54 through line 62 and high quality ethylene -is removed ina conventional ethylene recovery plant 64. Product ethylene serves theAsystem through line 66. The remaining product gases are passed throughline 68 into a conventional carbon dioxide -removal plant 70. The wastecarbon dioxide Iis vented from the system through line 72. The remaininggases cons-ist primarily of carbon monoxide, meth-ane, hydrogen, smallquantities of ethane and C3 to C7 hydrocarbons. These gases leave thecarbon dioxide plant through line 74 and are recycled back into thesystem. A portion of the recycled g-as can be fed directly into the charheater through 'line 20, where it picks up air required for combustionthrough compressor 22 and line 24. The remaining gases join thepyrolysis feed materials in line `8 and are recycled through thepyrolysis reactor being utilized as carrier gas and where they are usedas feedstock lto produce more ethylene.

EXAMPLE To illustrate the effect of our novel process, a comminutedsample of municipal waste from Middletown, Ohio was pyrolyzed at atemperature of 1400 F. Prior salvaging was conducted on the sample,removing nearly all metal, glass and other inert materials, and about50% of the paper fibers.

The primary organic residue of this municipal solid waste wascontinuously fed into the pyrolysis reactor zone at about three poundsper hour, and the particle size ranged from about 50 mesh to 1/2 inch.The turbulent stream in the reactor zone contained 7.2 Weight percentwater based upon the weight of the carbonaceous material in the stream.

Table 1 given as follows shows an analytical breakdown of the componentsof the wastes used in this example.

TABLE 1 Analysis of Oven-Dried Hydropulped Municipal Solid Waste fromMiddletown, Ohio Component: Weight percent Carbon 46.1 Hydrogen 7.7Sulfur 0.07 Nitrogen 0.65 IChlorine 0.13 Ash 6.5 LOxygen (by difference)39.8

NOTE: Over of the inert, inorganic materials were removed by the BlackClawson Company prior to pyrolysis.

Table 2 given as follows shows an analysis of the products produced upongasification of carbonaceous materials utilizing the process of thisinvention.

TABLE 2 [Products of gasification pyrolysis] Gas fraction, 86 wt.

percent; heating value 770 Btu/ft.

Char fraction, 7 wt. percent.

39.4 wt. percent- 54.1 Wt. percent 0.5 wt. percent. 3.2 wt. percentohirine. f

Oxygen (by difference).

Liquid fraction, 7 wt. percent; pH -3.5.

Over 90.0 wt. percent Water. Sulfur.

Over 0,04 wt. percent..

Also contains Acetaldehyde, acetic acid,

acetone, formic acid, furfural, methanol,

phenol, etc.

It will be obvious to anyone skilled in the art that our novel processprovides an eicient economical process not only of eliminating solidwastes but also provides a source of valuable raw materials for thechemical industry. Thus, it transforms a problem into a benefit. Basedon the results obtained in the example it is projected that a plantutilizing our novel process to process 2000 tons per day of municipaltrash would produce million pounds of ethylene per year at 86%conversion to gas with the process heat being supplied by thenon-ethylene portion of the said gas.

What is claimed is:

1. A process for producing gaseous hydrocarbons having from 1 to 7carbon atoms from solid carbonaceous material comprising:

a. Forming a turbulent gaseous stream composed of carrier gas, water,char, and particulate carbonaceous solids, said solids having anindividual maximum particle dimension of less than 1.0 inch, such thatthe solids and Water are intimately admixed and entrained within thegaseous portion of the stream;

said water being present in said stream in an amount which is at least2.0 weight percent based upon the amount of carbonaceous solids in saidstream; said carrier gas containing less than 1% by volume of oxygen;

b. Heating the components of said stream to a temperature ranging frombetween about 1200 F. and about 2500 F. in a pyrolysis zone for apredetermined residence time so that at least a portion of saidcarbonaceous solids are converted to gaseous hydrocarbons, containingfrom 1 to 7 carbon atoms, ethylene comprising at least 20% by volume ofsaid gaseous hydrocarbons;

c. Removing the product stream from the pyrolysis zone;

d. Recovering the gaseous hydrocarbon products.

2. The process of Claim 1 wherein the said gaseous stream contains fromabout 7 to about 18 weight percent water, based upon the weight ofcarbonaceous solids in the stream.

3. The process of Claim 2 wherein said gaseous stream is heated to atemperature ranging from between 1400' F. to about 1600 F. in saidpyrolysis zone.

4. The process of Claim 1 wherein said stream is heated to a temperatureof about 1500 F. in said pyrolysis zone.

S. The process of Claim 1 wherein the residence time of the carbonaceoussolids in said pyrolysis zone is less than 5 seconds.

6. The process of Claim 1 wherein the carbonaceous solids are municipalwaste material, sewage sludge, rubber tire scrap, agricultural wastes,manure, crop residue, food processing wastes, industrial wastes,lignocellulose products, and mixtures thereof.

7. The process of Claim 2 in which the carbonaceous solids are municipalwaste materials.

8. The process of Claim 2 wherein said carbonaceous solids are muniuipalwaste material, manure, sewage sludge, rubber tire scrap, foodprocessing wastes, agricultural wastes, industrial wastes,lignocellulose products, and mixtures thereof.

9. The process of Claim 2 wherein the gaseous hydrocarbons are separatedinto their component parts.

10. The process of Claim 1 wherein the gaseous hydrocarbons producedconsist substantially of ethylene.

11. The process of Claim 1 wherein a substantial portion of the heatrequired for pyrolysis of the carbonaceous solids is supplied byutilizing heated char in the gaseous stream.

12. The process of Claim 1 wherein a portion of the heat required in thepyrolysis Zone is supplied by indirect heating means to heat thecarbonaceous solids.

13. The process of Claim 2 wherein said carbonaceous solids are rubberscrap.

14. The process of Claim 2 wherein a portion of the solids recoveredfrom the product stream is separately heated to a temperature rangingfrom between about 1500 F. to about 2400 F. and thereafter is recycledthrough the pyrolysis zone as hot char in the gaseous stream to supply asubstantial portion of the heat required in the pyrolysis zone to heatthe carbonaceous solids.

15. The process of Claim 14 wherein sutlicient amounts of heated charare utilized to provide substantially all of the heat required to heatthe carbonaceous solids in the pyrolysis zone.

16. The process of Claim 14 wherein the carrier gas is a hydrogenenriched gas stream.

References Cited UNITED STATES PATENTS 3,511,194 5/1970 Stookey 48-209UX 3,615,300 10/1971 Holm 48--202 X 3,671,209 6/1972 Teichmann et al.48-209 3,687,646 8/1972 Brent et al. 48--209 3,715,195 2/1973 Tassoneyet al. 48-202 X R. E. SERWIN, Primary 'Examiner

1. A PROCESS FOR PRODUCING GASEOUS HYDROCARBONS HAVING FROM 1 TO 7CARBON ATOMS FROM SOLID CARBONACEOUS MATERIAL COMPRISING: A. FORMING ATURBULENT GASEOUS STREAM COMPOSED OF CARRIER GAS, WATER, CHAR, ANDPARTICULATE CARBONACEOUS SOLIDS, SAID SOLIDS HAVING AN INDIVIDUALMAXIMUM PARTICLE DIMENSION OF LESS THAN 1.0 INCH, SUCH THAT THE SOLIDSAND WATER ARE INTIMATELY ADMIXED AND ENTRAINED WITHIN THE GASEOUSPORTION OF THE STREAM SAID WATER BEING PRESENT IN SAID STREAM IN ANAMOUNT WHICH IS AT LEAST 2.0 WEIGHT PERCENT BASED UPON THE AMOUNT OFCARBONACEOUS SOLIDS IN SAID STREAM; SAID CARRIER GAS CONTAINING LESSTHAN 1% BY VOLUME OF OXYGEN; B. HEATING THE COMPONENTS OF SAID STREAM TOA TEMPERATURE RANGING FROM BETWEEN ABOUT 1200* F. AND ABOUT 2500* F. INA PYROLYSIS ZONE FOR A PREDETERMINED RESIDENCE TIME SO THAT AT LEAST APORTION OF SAID CARBONACEOUS SOLIDS ARE CONVERTED TO GASEOUS HYDROCAR